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I'm going to be breeding reptiles, so I'll need an incubator. I'm currently thinking about using tec coolers as a heater inside an insulated box. The issue I'm thinking I'll have is that with a cheap o controller with a probe like this one https://www.ebay.com/itm/223951905414 I may blow up something using a 3x 40mm 12v 6amp tec chip setup and two separate power supplies to reverse polarity. If there is an easier way to do this, that'd be great. All I need to do is get the air in the space to be warmed/cooled to 90 degrees f. Thanks for your time!

Caleb
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    What is your question? – The Photon Oct 19 '20 at 04:23
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    You realize simple resistors are literally heaters, right? Now cooling the air, that is a different story but a peltier can only *move* heat. Which means that if you want to cool the inside of the chamber, the peltier needs to be on the wall so that it sucks heat from the cold side and dumps onto the hot side. – DKNguyen Oct 19 '20 at 04:36
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    @DKNguyen To be fair, the TEC might be inefficient enough to heat the chamber even if it is just moving heat from one part of the chamber to the other. It would be a heck of a lot cheaper to just use a resistor, though. – The Photon Oct 19 '20 at 04:48
  • @ThePhoton I do use my PC tower as a space heater sometimes. – DKNguyen Oct 19 '20 at 04:49
  • I had not realized that, this may just be my ticket! This is why I posted, to find a more efficient idea! Thanks! – Caleb Oct 19 '20 at 16:52

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maybe you can try PTC heater, simple, efficient and cheaper.

Chengxian Zhang
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If you have two wires going into a closed volume, and pass electrical power in, then 100% of that power will be turned into heat (eventually).

If you have a simple resistor as the load, the capital cost is very low. If you have exotic materials or complicated systems, then you'll still get the heat, but it will cost more to build.

I'd suggest you use simple resistors, if you're going to control the heater externally. You might find a PTC resistor with a knee at your temperature which will do the heating and controlling job automatically.

Neil_UK
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  • If you need a lot of heat, heat pumps can be worth it because they convert *more* than 100% of the electricity into useful heat. – user253751 Oct 19 '20 at 08:56
  • @user253751 If you need a lot of heat, compression cycle heat pumps can be worth it. For typical temperature differences, the COP of Peltiers is so low that it's rarely a reason for choosing them, just spending the money on Joule heating is far easier, and usually cheaper as well if you finance the initial costs. Use Peltiers where you absolutely have to, for cooling, or temperature control near to ambient, where compression cycle coolers are too noisy or large. – Neil_UK Oct 19 '20 at 09:00
  • Thanks Niel. Moving away from peltier, what are you referring to when you say a 'knee'? Is this a self contained unit that i have not stumbled upon? I know a good bit about electronics and wiring, but programming and actually designing circuitry is new to me. – Caleb Oct 19 '20 at 16:58
  • Just did a Google. Look at this unit I found: https://www.amazon.com/dp/B07NYX5DKD/ref=cm_sw_r_cp_apa_i_PxCJFbZVH6SH5 this actually seems ideal! Am I to assume that a PTC thermistor generates more heat depending on the current applied? This could very well plug into a thermostat with little problems. – Caleb Oct 19 '20 at 17:02
  • Not really the thing I had in mind. The PTC has a knee at some unspecified high temperature. It gets very hot, and stays at that temperature. You control the heat output to the rest of the space by controlling the fan speed. If you had a PTC at 90 F, then it would do its own temperature controlling. That temperature controller you linked looks fine. Use it to control a power resistor, or filament lamp, inside the controlled volume. Especially, do not use it to control the PTC heater you linked. – Neil_UK Oct 19 '20 at 19:45